It is very common and has been known for a long time to add colloidal silicic acids in the field of the formulations of crop protection agents. The use is described sufficiently in the corresponding literature.
The use known from the prior art is limited to the use of the silica gels as so-called “inert” cocomponents in crop protection preparations. Thus, for example, the use of silica gels as auxiliaries for preparing dispersible suspensions is described in Bühel “Pflanzenschutz und Schädlingsbekämpfungsmittel”, 1977, page 198. In “Surfactants in Agrochemicals” 1995, page 155, Tadros describes the use of silica gels as additives for suspension concentrates to prevent sedimentation and caking. The use of silica gel as filler is described in Foy and Pritchard in “Pesticide Formulation and Adjuvant Technology”, 1996, page 85.
In Römpp, “Chemie Lexikon”, 1995, page 2233, under the entry “Kieselgele”, likewise only the properties and uses which are already known, inter alia as thixotropic agent, are described.
An increase in activity or a widening of the activity spectrum of, for example, herbicides having foliar action on weeds outside the known area of use on addition of silica gels has not been described and was also not to be expected.
To improve the activity of known crop protection agents, the prior art proposes specific additives or specific cocomponents developed for this purpose. In general, mineral oils and vegetable oils and their derivatives, and also specific surfactants, for example polysaccharides, ethoxylated triglycerides, ethylene oxide or propylene oxide copolymer adducts with ethylenediamine as central starter unit, polyethoxylated fatty acids and amides thereof and also ethoxylated alkylaryl alcohols having typically 6-10 oxyethylene units are employed here.
The amount of such additives or bioactivators that is required varies between 100 g/l of ready-to-use preparation to from 2 to 3 l per ha, for example in the case of the mineral and vegetable oils as tank mix partners of the herbicides having foliar action.
It was not possible with any of these products to extend the activity spectrum of, for example, active compounds employed as herbicides to other weeds and to improve the activity at the same time.
Recent studies have shown that the use of aqueous suspension concentrates generally offers advantages compared to emulsions. Thus, the use of solvents which are toxicologically and ecotoxicologically objectionable, such as, for example, isophorone, cyclohexanone, xylenes and acetophenone, can be dispensed with.
Moreover, the concentration of the active compounds can be considerably increased (cf. DE 43 29 974). These advantages reduce, for example, packaging, transport and also storage costs considerably.